X-ray micrographs of biological objects have been obtained with a resolution better than 1000 angstroms by using poly(methyl methacrylate) x-ray resist and carbon Kalpha or synchrotron radiation. Synchrotron radiation allows short exposure times; storage rings especially designed as radiation sources and improved x-ray resists would make exposure times under 1 second possible.

Synchrotron radiation from the German electron synchrotron DESY in Hamburg has been used for x-ray lithography. Replications of different master patterns (for magnetic bubble devices, Fresnel zone plates, etc.) were made using various wavelengths and exposures. High-quality lines down to 500 Å wide have been reproduced using very soft x rays. The sensitivities of x-ray resists have been evaluated over a wide range of exposures. Various critical factors (heating, radiation damage, etc.) involved with x-ray lithography using synchrotron radiation have been studied. General considerations of storage ring sources designed as radiation sources for x-ray lithography are discussed, together with a comparison with x-ray tube sources. The general conclusion is that x-ray lithography using synchrotron radiation offers considerable promise as a process for forming high-quality-submicron images with exposure times as short as a few seconds.

X-ray micrographs of biological materials have been obtained with a resolution better than 100 angstroms by using x-ray resist as the recording medium. A high-resolution scanning electron microscope with a short-focal-length final lens, operating in the "low-loss" mode, is used to make the smallest features in the x-ray replica visible.

The effective range of secondary electrons generated by Al Kα radiation is measured in polymethylmethacrylate (PMMA) as 400 Å. Lines with 0.1-μm linewidth with high aspect ratios are successfully replicated with x rays. Problems connected with the replication of very low contrast masks are discussed. Carbon Kα radiation is proposed as the radiation to be used for the replication of very fine geometries around or below 0.1 μm.

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